Disease relevance of ALF

• Recombinant ALF (69 kDa) and TFIIAgamma (12 kDa) polypeptides produced in Escherichia coli form an ALF/gamma complex that can stabilize TBP-TATA interactions in an electrophoretic mobility shift assay [1].
• The ALF/gamma complex is also able to restore transcription from the adenovirus major late promoter using HeLa cell nuclear extracts that have been depleted of TFIIA [1].
• These patients were further subclassified depending upon the interval between the onset of jaundice and the onset of encephalopathy into hyperacute (HALF; interval 0-7 days), acute (ALF; interval 8-28 days) and subacute liver failure (SALF; interval 4-12 weeks) [2].
• The product was sequenced automatically, by using an ALF Express automatic sequencer, to confirm the mycoplasma species and to identify the strain since the two genes were usually found to be polymorphic [3].
• Alpha interferon-2b, leucovorin, and 5-fluorouracil (ALF) in non-small cell lung cancer [4].

High impact information on ALF

• Regulatory Factor Interactions and Somatic Silencing of the Germ Cell-specific ALF Gene [5].
• Overall, the results suggest a role for several factors, including the multivalent zinc finger chromatin insulator protein CTCF, in mediating somatic repression of the ALF gene [5].
• In addition, RNAi-mediated down-regulation of CTCF is associated with activation of the endogenous ALF gene, and both CTCF and Sp3 repress the promoter in transient transfection assays [5].
• Thus, a role for ALF in the assembly and stabilization of initiation complexes in germ cells is likely to be similar or identical to the role of TFIIA in somatic cells [6].
• We also found that ALF expression correlates with a strong promoter-proximal DNase I-hypersensitive site present in nuclei from testis but not from liver [7].

Biological context of ALF

• In addition, in situ hybridization experiments with adult mouse testis shows that ALF is present in haploid spermatids [8].
• Searches of the human genome sequence database using the basic local alignment search tool reveal that the ALF and TFIIAalpha/beta(GTF2A1) genes are both composed of nine exons, whereas the TFIIAgamma (GTF2A2) gene is composed of five exons [8].
• The open reading frame of ALF predicts a protein of 478 amino acids that contains characteristic N- and C-terminal conserved domains separated by an internal nonconserved domain [1].
• Overall the results show that silencing in somatic cells is methylation-dependent and reversible and that a unique CpG-specific methylation pattern at the ALF promoter precedes expression in pachytene spermatocytes [7].
• However, phosphorylation of ALF with casein kinase II resulted in the partial restoration of complex formation using mutant TBPs [6].

Anatomical context of ALF

• Northern analysis shows that ALF mRNA first appears in mouse testis at Postnatal Day 14 [8].
• Analysis of male germ cells separated by Staput sedimentation shows that ALF is present in pachytene spermatocytes and haploid spermatids [8].
• Further, bisulfite sequence analysis of the mouse ALF promoter showed that all 21 CpG dinucleotides between -179 and +207 were partially methylated in five somatic tissues, brain, heart, liver, lung, and muscle, and in epididymal spermatozoa from adult mice [7].
• Finally we show that in vitro methylation of the ALF promoter inhibits activity and that 5-aza-2'-deoxycytidine treatment reactivates the endogenous ALF gene in a panel of seven different mouse and human somatic cell lines [7].
• ALF mRNA was also down-expressed in circulating HCC cells compared to circulating normal hepatocytes [9].

Associations of ALF with chemical compounds

• Incubation of ALF with sn-2 acyl PAF analogs indicated that the enzyme hydrolyzes the sn-2 fatty acid only if the chain length is five carbons or less, the sn-1 position fatty acid length is greater than 10 carbon units, and at least one methyl group is present on the terminal amine of the choline group [10].
• Preliminary studies of an acid-labile factor (ALF) in human sera that inactivates platelet-activating factor (PAF) [11].

Other interactions of ALF

• In addition, a rare ALF-containing cDNA, which possesses an extended N terminus (Stoned B/TFIIAalpha/beta-like factor; SALF) has also been identified [1].
• Thus, detection of ALF mRNA, in addition to that of alpha-fetoprotein (AFP) mRNA, might help to distinguish normal or malignant hepatocytes in peripheral blood [9].

Analytical, diagnostic and therapeutic context of ALF

• Finally, analysis of the distinct, nonhomologous internal regions of ALF and TFIIAalpha/beta using circular dichroism spectroscopy provided the first evidence to suggest that these domains are unordered, a result consistent with other genetic and biochemical properties [6].
• ALF is associated with low-density lipoproteins but can be dissociated from the lipoproteins with detergent followed by ultracentrifugation [12].

References